Proposed services for mobile terminals, such as news, entertainment or business services, require the transmission of content to one or more receiving devices. The content may include audio, video, multimedia, graphic or other data, such as music files or film clips. In view of the considerable amount of data needed to provide such services, a highly efficient transmission mechanism is required, such as a broadcasting mechanism.
However, a digital broadcast network cannot be used to send messages from a mobile terminal to a service provider, for example, when a user of the terminal wishes to subscribe to a service, discontinue a service, or send a negative acknowledgement notifying a service provider that data packets have not been properly received. This may be overcome by enabling communication between the service provider and mobile terminal over a second network, such as a cellular telecommunications network. Additionally, while the use of a broadcasting mechanism is efficient, it may be desirable to restrict access to content to users who have registered with and/or paid for a particular service.
One method of achieving this would be to encrypt the data using a key that is available only to registered terminals. However, this may require the transmission of decryption information to each registered mobile terminal individually, which may be uneconomical and reduce the efficiency gains associated with broadcasting.
Furthermore, a mechanism for associating a registration, sale or subscription made over the telephone network with content transmitted over the digital broadcast network is required. In addition, where content is made available on payment of a fee, it is necessary for information relating to the service (such as pricing information) to be synchronized with information used to process purchases made via a telephone network.